fix(packaging): include .config and .json data files in wheel

[0x5t4l1n]

Summary

Fixes #97.

Importing any xmlcli module that loads the config at import time (e.g. xmlcli.modules.nvram) raises configparser.NoSectionError: No section: 'GENERAL_SETTINGS' when xmlcli is installed from a wheel.

Root cause

The project uses poetry-core as its build backend ([build-system] in pyproject.toml). Poetry's build backend does not read setup.cfg or MANIFEST.in, so the non-Python data files (xmlcli.config, messages.json, everything under cfg/) are silently omitted from the wheel even though MANIFEST.in lists them for sdist builds.

Fix

Add an explicit include list to [tool.poetry] so Poetry bundles the required data files in both the sdist and the wheel:

[tool.poetry]
packages = [{include = "xmlcli", from = "src"}]
include = [
    {path = "src/xmlcli/xmlcli.config", format = ["sdist", "wheel"]},
    {path = "src/xmlcli/messages.json",  format = ["sdist", "wheel"]},
    {path = "src/xmlcli/cfg/**/*",       format = ["sdist", "wheel"]},
]

Verification

python -m build          # build the wheel
pip install dist/*.whl   # install from wheel
python -c "import xmlcli.modules.nvram"  # no longer raises NoSectionError